Cross derailleur

The Cross derailleur used a design patented and manufactured by Novitas Fabrik Elektrischer Apparate A.G. of Zürich, Switzerland in 1932.

It is a simple, robust, touring (rather than racing) design. The cable pull rotates a drum with a spiral surface cut into its inside surface. This spiral acts on a bolt head screwed into the main rod that holds the pulley cage, moving it in and out as the drum rotates. All this is very reminiscent of the contemporary Cyclo designs. However, unlike the double cable, unsprung Cyclo, Novitas opted for a single cable with a spring in the derailleur. This spring pulls the guide pulley outwards - making the derailleur top normal. The derailleur also has rather well shielded moving parts - meaning that the grease was likely to stay in, and the road crap was likely to stay out.

I believe that the Novitas's basic design went through (perhaps) seven development stages:

The initial version (1934?) had an external pulley cage spring that led from the tension pulley bolt to a fixing on the rear dropout. Initially the pulley cage arm was short (55mm centre to centre) and the tension pulley had large (60mm) flanges. The very first models had a well-finished, countersunk, round hole in the flange that accepts the cable nipple.
The second version (1935?) had a rather crude, rectangular hole in the flange that accepts the cable nipple.
A third version (1937?) was largely identical - but had a longer (70mm) pulley cage arm.
A fourth version (1938?) moved the pulley cage spring so that it led from an eyelet at the top of the pulley cage arm, along the chainstay to a clip. The tension pulley was also reduced in size to 50mm diameter. Finally this version, like all previous versions, had a steel pulley cage arm.
A fifth version (also 1938?) was identical to the fourth version, except that it had an aluminium pulley cage arm.
The sixth version (1939?) was an extensive, but only partially successful redesign. The mounting bracket was made of thinner guage steel, the 72mm pulley cage arm was narrower, the cap at the end of the main cylinder became aluminium.
The seventh version (possibly later 1939?) was largely identical, but the sliding cylinder mechanism was made of moderately accurately machined steel, rather than beautifully finished brass.

These dates are a touch spurious. The 1932 date of the founding patent is not in doubt. The 1934 date for the appearance of the first production derailleurs comes from The Dancing Chain. I have some adverts from 1936 also showing the first or second generation. And at that point my hard data really stops. If you have any 1930s catalogues which have real detail, I would be very interested!

I think this is a, reasonably tidy, example of a Cross derailleur from the sixth generation described above. Some key features are:

The main mounting bracket is made of 2mm guage steel.
It has a brass cable adjuster at the point that the cable passes through the mounting plate.
The main operating cylinder has a steel internal mechanism and an aluminium end cap.
The mounting hole for the cable nipple is somewhat rectangular.
The pulley cage spring attaches to the top of the pulley arm.
The steel pulley cage arm is about 12mm wide and 72mm centre to centre.
The tension pulley flanges are 50mm in diameter.
The tension pulley has 'CROSS BREVETÉ S.G.D.G.' engraved in it.

Derailleur brands: Cross manufactured by Novitas Fabrik Elektrischer Apparate A.G.
Country: Switzerland
Date of introduction: 1939?
Date of this example: unknown
Model no.: unknown
Weight: 300g excluding mounting bolts and pulley cage spring
Maximum cog: unknown
Total capacity: unknown
Pulley centre to centre: 72mm
Index compatibility: friction
Chain width: 1/8”
Logic: top normal
B pivot: none
P pivot: sprung
Materials: mainly steel with some brass small parts and an aluminium tension pulley flanges

Ref. 1938